A conventional perpendicular recording head typically employs an inductive transducer positioned in close proximity to a magnetic medium. The inductive transducer is comprised of a plurality of pole and shield layers, a plurality of coils for generating a magnetic field, and a pole tip. The induced magnetic field during a write operation generates magnetic flux lines that traverse through the magnetic recording medium from the pole tip.
The efficiency of a perpendicular recording head depends on several factors that control the operation of the magnetic field, such as the write gap, the track width of the pole tip, and the throat height. Another such factor also depends on the shape of the third shield layer. Generally, the third shield layer is disposed at the air bearing surface (ABS) of the recording head, and is formed integrally with the top shield layer, that is also known as the fourth shield layer. In a conventional perpendicular recording head, the width of the third shield layer is relatively wide, and is substantially greater than the track width of the pole tip. Typically, the width of the third shield layer is on the order of 50 μm.
The disparity between the width of the third shield layer and the track width of the pole tip creates a number of problems for the conventional perpendicular recording head. As an example, because of the width of the third shield layer, plating seems to be the most suitable manufacturing process for creating the third shield layer. Plating process typically requires a high level of complexity towards achieving the maximum possible magnetic moment. As a result, other methods of generating higher moment, such as sputtering, may not be adequately used with the conventional perpendicular recording head employing a wide third shield layer.
Another problem associated with a wide third shield layer is the manufacturing complexity and high cycle time required for manufacturing the conventional perpendicular recording head at the wafer level. Generally, the pole tip width must first be defined by a complex topography on the wafer. The following step includes a planarization process. However, during planarization, pole tips and/or write gaps may be subjected to potential damage. As a result, the planarization process must be performed in a high degree of exactness, which significantly contributes to the cycle time of the head. Once the planarization step is completed, the third shield layer may be formed.
Yet another problem encountered with manufacturing a conventional perpendicular recording head employing a wide third shield layer lies in the fabrication of the pole tip. Typically, the pole tip ABS view is shaped as a trapezoid. In the conventional perpendicular recording head, the trapezoidal pole tip cross section has to be defined first, separately from the third shield layer. The process of defining the trapezoidal pole tip generally requires a separate pole trim process. However, during this process, there exists a possibility of track width variation and pole tip thickness variation when using a metal mask; and, when using an aluminum mask or a hard mask this poses another challenge in the removal of the mask. In either case, it would be relatively difficult to implement these two processes.
Therefore, what is needed is an improved shielded pole magnetic head design for perpendicular recording that includes a novel third shield layer design in order to overcome the current problems. The new third shield design would substantially reduce the manufacturing complexity, and would further enable the use of more efficient methods for depositing high moment materials such as sputtering. It would also be desirable to present an improved pole trim process that would result in improved track width uniformity of the write pole tips across the wafer.